Effects of acrolein on stomatal aperture and cytosolic alkalization in Arabidopsis guard cells. (A) Acrolein-induced stomatal closure in WT and tgg mutants, tgg1-3, tgg2-1 and tgg1-3 tgg2-1. (B) Representative images of the epidermal tissues containing guard cells of WT, tgg1-3, tgg2-1 and tgg1-3 tgg2-1. Excised rosette leaves were treated with acrolein for 2 h. Averages from three (n = 3) independent experiments (60 total stomata per bar) are shown. Scale bar = 5 µm. (C) Effects of acrolein on BCECF fluorescence in guard cells of WT, tgg1-3, tgg2-1 and tgg1-3 tgg2-1. The vertical axis shows the percentage of BCECF fluorescence when fluorescent intensities of acrolein-treated cells are normalized to the control value taken as 100% for each experiment. Each data was obtained from at least 90 guard cells. (D) Representative BCECF fluorescence images of the epidermal tissues containing guard cells of WT, tgg1-3, tgg2-1 and tgg1-3 tgg2-1. Scale bar = 20 µm. The error bar represents the standard error. Differences between treatments were analyzed by Student’s t-test: *P < 0.05 and **P < 0.01.